Transportation of sediments by floating processes from southern Europe to the coastal regions of eastern Libya: Pumice rock fragments from at Tariyah and Qasr Libya coasts1

Abstract

Fragments of pumice of various sizes and roundness were found mixed with recent coastal sediments of calcareous sand, calcareous granules, and shells in At Tariyah coast southwest of Benghazi, and in the coastal area of Qasr-Libya, Al Jabal Al Akhdar, northeastern Libya. The source area for the pumice fragments appears to be the active volcanic regions of eastern and southern Sicily; Etna volcano and submarine volcano known as the CampiFlegrei del Mar di Sicilia respectively. The pumice must have traveled a distance of at least 1000km across the Mediterranean Sea as a floating load. The recent coastal sediments of the Al Jabal Al Akhdar area are derived mainly from two different sources; a southern proximal source consisting of a well-exposed sequence of Tertiary carbonate rocks that produced well-sorted sand-size fragments and a northern distal source that produced cobble-size fragments of pumice. The mechanism of transporting sediments by floating as a floating load, from one sedimentary basin to another is completely different from the other well-known and documented methods of bedload and suspended load. Floating fragments can be transported for long distances and finally deposited without appreciable changes in size, roundness, shape, or sorting. Pumice deposited on the eastern coast of Libya indicates that long-distance transport produces minimal or negligible changes in the textural parameters of floating load components